The present application relates broadly to measurement apparatus, and in particular to a low contrast measurement apparatus for the measurement of low contrast ratios on video signals in television systems.
In the prior art, it is an established fact that an observer can identify a low contrast scene on a TV monitor even when the trace of the video signal on an oscilloscope does not show any measurable modulation. As a result there exists a need to be able to electronically measure the condition, since camera performance standards are usually given in terms of variations of the video output signal. Therefore, new techniques have to be developed to measure changes in the video signal which represent a very low contrast scenes. The sensitivity of the electronic measuring device has to reach or surpass the discrimination capability of the eye of an human observer. These techniques, in turn, have to be suitable for obtaining quantitative results which may be used to define new standards.